Saturday, April 23, 2011

Catholic and Protestant fertility over time

Talking to my dad and brother, we somehow got into Catholic fertility in the US. After describing a family with five or six kids, it's still fairly common to hear the quip, "Are they Catholic?" I'm aware of the stereotype, though it wasn't formed from actual firsthand experience. The more noticeable distinction I've picked up on is between those who are genuinely religious and those who are only nominally so (or not at all). My dad guessed greater Catholic fertility remained the case today, though maybe not as pronounced as it had been when he was growing up.

Fortunately, the GSS contains relevant self-reported data on the question extending back to the early seventies. The following graph shows the mean number of children among white Protestants and Catholics in the US over time. To avoid issues with uncompleted procreation while simultaneously trying to minimize unnecessary overlap, only respondents in their forties at the time they participated in the survey are included. The question does not specifically inquire exclusively about biological children, but it insinuates as much. A handful of respondents likely included adopted or step children, but the number is probably insignificant and anyway presumably effects both Protestant and Catholic respondents equally:

Looks like the fecundity gap exists and was a bit wider a generation ago than it is now, but over the last four decades at least has not been very significant and is barely existent at all today.

From the view of the churches, though, Catholics do have the upper hand, since among Hispanics in the US Catholics outnumber Protestants by about five-to-one, and Hispanic birthrates are far higher than white birthrates are.

Does the GSS break Protestant fecundity down by denomination? I would like to see data on liberal (eg Episcopalian) vs. conservative (eg Southern Baptists) birth rates.

By the way, I'm 67. I was raised French-Canadian Catholic. (Yes, there is a difference.) My parents had 5 kids, and my 4 sisters had 16 among them. I had 2. Their children are having fewer kids. So we followed the general curve downwards with a lag.

Are you aware of a good source of the Mormon TFR in the US? The Pew religious landscape survey looks at kids under 18 living at home (and the Mormon number is significantly higher than it is for other white Christian groups), but that's only a rough proxy.

In 2003, Utah's TFR, at 2.6, was the highest in the nation. The Hispanic TFR in the US that year was 2.8. Presuming that non-Mormons living in Utah have lower TFRs than their Mormon neighbors do, it looks like they're about neck and neck.

Sykes,

It does, although sample sizes get a little small. If we're willing to expand the age range a little wider, it'd be more reliable.

"The Mormon Church, however, doesn't appear to want to beat them, it wants to join them--or have them join it."

As my brother said, "want in one hand, sh't in the other and see which fills faster." Point is Mormons exercise church discipline. They kick you out for being a loser. Sure, they invite tons of folks, but who can live up to their laws? Not a bunch of Mestizos that is for sure. The only folks who can stay Mormon have to have self control. That is why their birthrate goes up with income, not down like everyone else. I am talking about Mormons in good standing, not Utah residents with some family heritage/association with the LDS. The religion/LDS church itself selects for conscientiousness and fitness in the Darwinian sense. I wouldn't even worry about blacks who are Mormons in good standing.

Talk to any babyboomer and they will tell you about the large Catholic family who lived down the block when they grew up. The change resulted when the Catholic babyboomer kids choose not to replicate the fertility of their WW2 generation parents. All of the Catholic babyboomers I personally (in their 50's today) have one or two kids.

It would be interesting to control for Church attendance. Catholics are so large a group that they regress to the mean on nearly every issue. But Catholics attending one or more per week are definitely different from those who never or almost never attend. Also, as one commenter pointed out, there a stark difference in the religion practiced by liberal Protestants and conservative ones--more stark, I think, than the divide between Protestants and Catholics.